SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2b6c46e9fdc1846f3984af666f68797f73a1fc111ad3b978226473d9603cf755' 
  AND token = '9a9ZQPYYyBnS5D+jw1YDCmYBb6M1yFK7YdqmYi/vuuo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}